summaryrefslogtreecommitdiff
path: root/lisp/ruler-mode.el
blob: 7deca94e67588ac16d43c7229d6463b54e7a9cd0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
;;; ruler-mode.el --- display a ruler in the header line

;; Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006,
;;   2007, 2008 Free Software Foundation, Inc.

;; Author: David Ponce <david@dponce.com>
;; Maintainer: David Ponce <david@dponce.com>
;; Created: 24 Mar 2001
;; Version: 1.6
;; Keywords: convenience

;; This file is part of GNU Emacs.

;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 3, or (at
;; your option) any later version.

;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; This library provides a minor mode to display a ruler in the header
;; line.  It works from Emacs 21 onwards.
;;
;; You can use the mouse to change the `fill-column' `comment-column',
;; `goal-column', `window-margins' and `tab-stop-list' settings:
;;
;; [header-line (shift down-mouse-1)] set left margin end to the ruler
;; graduation where the mouse pointer is on.
;;
;; [header-line (shift down-mouse-3)] set right margin beginning to
;; the ruler graduation where the mouse pointer is on.
;;
;; [header-line down-mouse-2] Drag the `fill-column', `comment-column'
;; or `goal-column' to a ruler graduation.
;;
;; [header-line (control down-mouse-1)] add a tab stop to the ruler
;; graduation where the mouse pointer is on.
;;
;; [header-line (control down-mouse-3)] remove the tab stop at the
;; ruler graduation where the mouse pointer is on.
;;
;; [header-line (control down-mouse-2)] or M-x
;; `ruler-mode-toggle-show-tab-stops' toggle showing and visually
;; editing `tab-stop-list' setting.  The `ruler-mode-show-tab-stops'
;; option controls if the ruler shows tab stops by default.
;;
;; In the ruler the character `ruler-mode-current-column-char' shows
;; the `current-column' location, `ruler-mode-fill-column-char' shows
;; the `fill-column' location, `ruler-mode-comment-column-char' shows
;; the `comment-column' location, `ruler-mode-goal-column-char' shows
;; the `goal-column' and `ruler-mode-tab-stop-char' shows tab stop
;; locations.  Graduations in `window-margins' and `window-fringes'
;; areas are shown with a different foreground color.
;;
;; It is also possible to customize the following characters:
;;
;; - `ruler-mode-basic-graduation-char' character used for basic
;;   graduations ('.' by default).
;; - `ruler-mode-inter-graduation-char' character used for
;;   intermediate graduations ('!' by default).
;;
;; The following faces are customizable:
;;
;; - `ruler-mode-default' the ruler default face.
;; - `ruler-mode-fill-column' the face used to highlight the
;;   `fill-column' character.
;; - `ruler-mode-comment-column' the face used to highlight the
;;   `comment-column' character.
;; - `ruler-mode-goal-column' the face used to highlight the
;;   `goal-column' character.
;; - `ruler-mode-current-column' the face used to highlight the
;;   `current-column' character.
;; - `ruler-mode-tab-stop' the face used to highlight tab stop
;;   characters.
;; - `ruler-mode-margins' the face used to highlight graduations
;;   in the `window-margins' areas.
;; - `ruler-mode-fringes' the face used to highlight graduations
;;   in the `window-fringes' areas.
;; - `ruler-mode-column-number' the face used to highlight the
;;   numbered graduations.
;;
;; `ruler-mode-default' inherits from the built-in `default' face.
;; All `ruler-mode' faces inherit from `ruler-mode-default'.
;;
;; WARNING: To keep ruler graduations aligned on text columns it is
;; important to use the same font family and size for ruler and text
;; areas.
;;
;; You can override the ruler format by defining an appropriate
;; function as the buffer-local value of `ruler-mode-ruler-function'.

;; Installation
;;
;; To automatically display the ruler in specific major modes use:
;;
;;    (add-hook '<major-mode>-hook 'ruler-mode)
;;

;;; History:
;;

;;; Code:
(eval-when-compile
  (require 'wid-edit))
(require 'scroll-bar)
(require 'fringe)

(defgroup ruler-mode nil
  "Display a ruler in the header line."
  :version "22.1"
  :group 'convenience)

(defcustom ruler-mode-show-tab-stops nil
  "*If non-nil the ruler shows tab stop positions.
Also allowing to visually change `tab-stop-list' setting using
<C-down-mouse-1> and <C-down-mouse-3> on the ruler to respectively add
or remove a tab stop.  \\[ruler-mode-toggle-show-tab-stops] or
<C-down-mouse-2> on the ruler toggles showing/editing of tab stops."
  :group 'ruler-mode
  :type 'boolean)

;; IMPORTANT: This function must be defined before the following
;; defcustoms because it is used in their :validate clause.
(defun ruler-mode-character-validate (widget)
  "Ensure WIDGET value is a valid character value."
  (save-excursion
    (let ((value (widget-value widget)))
      (if (char-valid-p value)
          nil
        (widget-put widget :error
                    (format "Invalid character value: %S" value))
        widget))))

(defcustom ruler-mode-fill-column-char (if (char-displayable-p ?¶)
                                           ?\¶
                                         ?\|)
  "*Character used at the `fill-column' location."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-comment-column-char ?\#
  "*Character used at the `comment-column' location."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-goal-column-char ?G
  "*Character used at the `goal-column' location."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-current-column-char (if (char-displayable-p ?¦)
                                              ?\¦
                                            ?\@)
  "*Character used at the `current-column' location."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-tab-stop-char ?\T
  "*Character used at `tab-stop-list' locations."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-basic-graduation-char ?\.
  "*Character used for basic graduations."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-inter-graduation-char ?\!
  "*Character used for intermediate graduations."
  :group 'ruler-mode
  :type '(choice
          (character :tag "Character")
          (integer :tag "Integer char value"
                   :validate ruler-mode-character-validate)))

(defcustom ruler-mode-set-goal-column-ding-flag t
  "*Non-nil means do `ding' when `goal-column' is set."
  :group 'ruler-mode
  :type 'boolean)

(defface ruler-mode-default
  '((((type tty))
     (:inherit default
               :background "grey64"
               :foreground "grey50"
               ))
    (t
     (:inherit default
               :background "grey76"
               :foreground "grey64"
               :box (:color "grey76"
                            :line-width 1
                            :style released-button)
               )))
  "Default face used by the ruler."
  :group 'ruler-mode)

(defface ruler-mode-pad
  '((((type tty))
     (:inherit ruler-mode-default
               :background "grey50"
               ))
    (t
     (:inherit ruler-mode-default
               :background "grey64"
               )))
  "Face used to pad inactive ruler areas."
  :group 'ruler-mode)

(defface ruler-mode-margins
  '((t
     (:inherit ruler-mode-default
               :foreground "white"
               )))
  "Face used to highlight margin areas."
  :group 'ruler-mode)

(defface ruler-mode-fringes
  '((t
     (:inherit ruler-mode-default
               :foreground "green"
               )))
  "Face used to highlight fringes areas."
  :group 'ruler-mode)

(defface ruler-mode-column-number
  '((t
     (:inherit ruler-mode-default
               :foreground "black"
               )))
  "Face used to highlight number graduations."
  :group 'ruler-mode)

(defface ruler-mode-fill-column
  '((t
     (:inherit ruler-mode-default
               :foreground "red"
               )))
  "Face used to highlight the fill column character."
  :group 'ruler-mode)

(defface ruler-mode-comment-column
  '((t
     (:inherit ruler-mode-default
               :foreground "red"
               )))
  "Face used to highlight the comment column character."
  :group 'ruler-mode)

(defface ruler-mode-goal-column
  '((t
     (:inherit ruler-mode-default
               :foreground "red"
               )))
  "Face used to highlight the goal column character."
  :group 'ruler-mode)

(defface ruler-mode-tab-stop
  '((t
     (:inherit ruler-mode-default
               :foreground "steelblue"
               )))
  "Face used to highlight tab stop characters."
  :group 'ruler-mode)

(defface ruler-mode-current-column
  '((t
     (:inherit ruler-mode-default
               :weight bold
               :foreground "yellow"
               )))
  "Face used to highlight the `current-column' character."
  :group 'ruler-mode)


(defsubst ruler-mode-full-window-width ()
  "Return the full width of the selected window."
  (let ((edges (window-edges)))
    (- (nth 2 edges) (nth 0 edges))))

(defsubst ruler-mode-window-col (n)
  "Return a column number relative to the selected window.
N is a column number relative to selected frame."
  (- n
     (car (window-edges))
     (or (car (window-margins)) 0)
     (fringe-columns 'left)
     (scroll-bar-columns 'left)))

(defun ruler-mode-mouse-set-left-margin (start-event)
  "Set left margin end to the graduation where the mouse pointer is on.
START-EVENT is the mouse click event."
  (interactive "e")
  (let* ((start (event-start start-event))
         (end   (event-end   start-event))
         col w lm rm)
    (when (eq start end) ;; mouse click
      (save-selected-window
        (select-window (posn-window start))
        (setq col (- (car (posn-col-row start)) (car (window-edges))
                     (scroll-bar-columns 'left))
              w   (- (ruler-mode-full-window-width)
                     (scroll-bar-columns 'left)
                     (scroll-bar-columns 'right)))
        (when (and (>= col 0) (< col w))
          (setq lm (window-margins)
                rm (or (cdr lm) 0)
                lm (or (car lm) 0))
          (message "Left margin set to %d (was %d)" col lm)
          (set-window-margins nil col rm))))))

(defun ruler-mode-mouse-set-right-margin (start-event)
  "Set right margin beginning to the graduation where the mouse pointer is on.
START-EVENT is the mouse click event."
  (interactive "e")
  (let* ((start (event-start start-event))
         (end   (event-end   start-event))
         col w lm rm)
    (when (eq start end) ;; mouse click
      (save-selected-window
        (select-window (posn-window start))
        (setq col (- (car (posn-col-row start)) (car (window-edges))
                     (scroll-bar-columns 'left))
              w   (- (ruler-mode-full-window-width)
                     (scroll-bar-columns 'left)
                     (scroll-bar-columns 'right)))
        (when (and (>= col 0) (< col w))
          (setq lm  (window-margins)
                rm  (or (cdr lm) 0)
                lm  (or (car lm) 0)
                col (- w col 1))
          (message "Right margin set to %d (was %d)" col rm)
          (set-window-margins nil lm col))))))

(defvar ruler-mode-dragged-symbol nil
  "Column symbol dragged in the ruler.
That is `fill-column', `comment-column', `goal-column', or nil when
nothing is dragged.")

(defun ruler-mode-mouse-grab-any-column (start-event)
  "Drag a column symbol on the ruler.
Start dragging on mouse down event START-EVENT, and update the column
symbol value with the current value of the ruler graduation while
dragging.  See also the variable `ruler-mode-dragged-symbol'."
  (interactive "e")
  (setq ruler-mode-dragged-symbol nil)
  (let* ((start (event-start start-event))
         col newc oldc)
    (save-selected-window
      (select-window (posn-window start))
      (setq col  (ruler-mode-window-col (car (posn-col-row start)))
            newc (+ col (window-hscroll)))
      (and
       (>= col 0) (< col (window-width))
       (cond

        ;; Handle the fill column.
        ((eq newc fill-column)
         (setq oldc fill-column
               ruler-mode-dragged-symbol 'fill-column)
         t) ;; Start dragging

        ;; Handle the comment column.
        ((eq newc comment-column)
         (setq oldc comment-column
               ruler-mode-dragged-symbol 'comment-column)
         t) ;; Start dragging

        ;; Handle the goal column.
        ;; A. On mouse down on the goal column character on the ruler,
        ;;    update the `goal-column' value while dragging.
        ;; B. If `goal-column' is nil, set the goal column where the
        ;;    mouse is clicked.
        ;; C. On mouse click on the goal column character on the
        ;;    ruler, unset the goal column.
        ((eq newc goal-column)          ; A. Drag the goal column.
         (setq oldc goal-column
               ruler-mode-dragged-symbol 'goal-column)
         t) ;; Start dragging

        ((null goal-column)             ; B. Set the goal column.
         (setq oldc goal-column
               goal-column newc)
         ;; mouse-2 coming AFTER drag-mouse-2 invokes `ding'.  This
         ;; `ding' flushes the next messages about setting goal
         ;; column.  So here I force fetch the event(mouse-2) and
         ;; throw away.
         (read-event)
         ;; Ding BEFORE `message' is OK.
         (when ruler-mode-set-goal-column-ding-flag
           (ding))
         (message "Goal column set to %d (click on %s again to unset it)"
                  newc
                  (propertize (char-to-string ruler-mode-goal-column-char)
                              'face 'ruler-mode-goal-column))
         nil) ;; Don't start dragging.
        )
       (if (eq 'click (ruler-mode-mouse-drag-any-column-iteration
                       (posn-window start)))
           (when (eq 'goal-column ruler-mode-dragged-symbol)
             ;; C. Unset the goal column.
             (set-goal-column t))
         ;; At end of dragging, report the updated column symbol.
         (message "%s is set to %d (was %d)"
                  ruler-mode-dragged-symbol
                  (symbol-value ruler-mode-dragged-symbol)
                  oldc))))))

(defun ruler-mode-mouse-drag-any-column-iteration (window)
  "Update the ruler while dragging the mouse.
WINDOW is the window where occurred the last down-mouse event.
Return the symbol `drag' if the mouse has been dragged, or `click' if
the mouse has been clicked."
  (let ((drags 0)
        event)
    (track-mouse
      (while (mouse-movement-p (setq event (read-event)))
        (setq drags (1+ drags))
        (when (eq window (posn-window (event-end event)))
          (ruler-mode-mouse-drag-any-column event)
          (force-mode-line-update))))
    (if (and (zerop drags) (eq 'click (car (event-modifiers event))))
        'click
      'drag)))

(defun ruler-mode-mouse-drag-any-column (start-event)
  "Update the value of the symbol dragged on the ruler.
Called on each mouse motion event START-EVENT."
  (let* ((start (event-start start-event))
         (end   (event-end   start-event))
         col newc)
    (save-selected-window
      (select-window (posn-window start))
      (setq col  (ruler-mode-window-col (car (posn-col-row end)))
            newc (+ col (window-hscroll)))
      (when (and (>= col 0) (< col (window-width)))
        (set ruler-mode-dragged-symbol newc)))))

(defun ruler-mode-mouse-add-tab-stop (start-event)
  "Add a tab stop to the graduation where the mouse pointer is on.
START-EVENT is the mouse click event."
  (interactive "e")
  (when ruler-mode-show-tab-stops
    (let* ((start (event-start start-event))
           (end   (event-end   start-event))
           col ts)
      (when (eq start end) ;; mouse click
        (save-selected-window
          (select-window (posn-window start))
          (setq col (ruler-mode-window-col (car (posn-col-row start)))
                ts  (+ col (window-hscroll)))
          (and (>= col 0) (< col (window-width))
               (not (member ts tab-stop-list))
               (progn
                 (message "Tab stop set to %d" ts)
                 (setq tab-stop-list (sort (cons ts tab-stop-list)
                                           #'<)))))))))

(defun ruler-mode-mouse-del-tab-stop (start-event)
  "Delete tab stop at the graduation where the mouse pointer is on.
START-EVENT is the mouse click event."
  (interactive "e")
  (when ruler-mode-show-tab-stops
    (let* ((start (event-start start-event))
           (end   (event-end   start-event))
           col ts)
      (when (eq start end) ;; mouse click
        (save-selected-window
          (select-window (posn-window start))
          (setq col (ruler-mode-window-col (car (posn-col-row start)))
                ts  (+ col (window-hscroll)))
          (and (>= col 0) (< col (window-width))
               (member ts tab-stop-list)
               (progn
                 (message "Tab stop at %d deleted" ts)
                 (setq tab-stop-list (delete ts tab-stop-list)))))))))

(defun ruler-mode-toggle-show-tab-stops ()
  "Toggle showing of tab stops on the ruler."
  (interactive)
  (setq ruler-mode-show-tab-stops (not ruler-mode-show-tab-stops))
  (force-mode-line-update))

(defvar ruler-mode-map
  (let ((km (make-sparse-keymap)))
    (define-key km [header-line down-mouse-1]
      #'ignore)
    (define-key km [header-line down-mouse-3]
      #'ignore)
    (define-key km [header-line down-mouse-2]
      #'ruler-mode-mouse-grab-any-column)
    (define-key km [header-line (shift down-mouse-1)]
      #'ruler-mode-mouse-set-left-margin)
    (define-key km [header-line (shift down-mouse-3)]
      #'ruler-mode-mouse-set-right-margin)
    (define-key km [header-line (control down-mouse-1)]
      #'ruler-mode-mouse-add-tab-stop)
    (define-key km [header-line (control down-mouse-3)]
      #'ruler-mode-mouse-del-tab-stop)
    (define-key km [header-line (control down-mouse-2)]
      #'ruler-mode-toggle-show-tab-stops)
    (define-key km [header-line (shift mouse-1)]
      'ignore)
    (define-key km [header-line (shift mouse-3)]
      'ignore)
    (define-key km [header-line (control mouse-1)]
      'ignore)
    (define-key km [header-line (control mouse-3)]
      'ignore)
    (define-key km [header-line (control mouse-2)]
      'ignore)
    km)
  "Keymap for ruler minor mode.")

(defvar ruler-mode-header-line-format-old nil
  "Hold previous value of `header-line-format'.")

(defvar ruler-mode-ruler-function 'ruler-mode-ruler
  "Function to call to return ruler header line format.
This variable is expected to be made buffer-local by modes.")

(defconst ruler-mode-header-line-format
  '(:eval (funcall ruler-mode-ruler-function))
  "`header-line-format' used in ruler mode.
Call `ruler-mode-ruler-function' to compute the ruler value.")

;;;###autoload
(define-minor-mode ruler-mode
  "Display a ruler in the header line if ARG > 0."
  nil nil
  ruler-mode-map
  :group 'ruler-mode
  (if ruler-mode
      (progn
        ;; When `ruler-mode' is on save previous header line format
        ;; and install the ruler header line format.
        (when (and (local-variable-p 'header-line-format)
		   (not (local-variable-p 'ruler-mode-header-line-format-old)))
          (set (make-local-variable 'ruler-mode-header-line-format-old)
               header-line-format))
        (setq header-line-format ruler-mode-header-line-format)
        (add-hook 'post-command-hook 'force-mode-line-update nil t))
    ;; When `ruler-mode' is off restore previous header line format if
    ;; the current one is the ruler header line format.
    (when (eq header-line-format ruler-mode-header-line-format)
      (kill-local-variable 'header-line-format)
      (when (local-variable-p 'ruler-mode-header-line-format-old)
        (setq header-line-format ruler-mode-header-line-format-old)
        (kill-local-variable 'ruler-mode-header-line-format-old)))
    (remove-hook 'post-command-hook 'force-mode-line-update t)))

;; Add ruler-mode to the minor mode menu in the mode line
(define-key mode-line-mode-menu [ruler-mode]
  `(menu-item "Ruler" ruler-mode
              :button (:toggle . ruler-mode)))

(defconst ruler-mode-ruler-help-echo
  "\
S-mouse-1/3: set L/R margin, \
mouse-2: set goal column, \
C-mouse-2: show tabs"
  "Help string shown when mouse is over the ruler.
`ruler-mode-show-tab-stops' is nil.")

(defconst ruler-mode-ruler-help-echo-when-goal-column
  "\
S-mouse-1/3: set L/R margin, \
C-mouse-2: show tabs"
  "Help string shown when mouse is over the ruler.
`goal-column' is set and `ruler-mode-show-tab-stops' is nil.")

(defconst ruler-mode-ruler-help-echo-when-tab-stops
  "\
C-mouse1/3: set/unset tab, \
C-mouse-2: hide tabs"
  "Help string shown when mouse is over the ruler.
`ruler-mode-show-tab-stops' is non-nil.")

(defconst ruler-mode-fill-column-help-echo
  "drag-mouse-2: set fill column"
  "Help string shown when mouse is on the fill column character.")

(defconst ruler-mode-comment-column-help-echo
  "drag-mouse-2: set comment column"
  "Help string shown when mouse is on the comment column character.")

(defconst ruler-mode-goal-column-help-echo
  "\
drag-mouse-2: set goal column, \
mouse-2: unset goal column"
  "Help string shown when mouse is on the goal column character.")

(defconst ruler-mode-margin-help-echo
  "%s margin %S"
  "Help string shown when mouse is over a margin area.")

(defconst ruler-mode-fringe-help-echo
  "%s fringe %S"
  "Help string shown when mouse is over a fringe area.")

(defsubst ruler-mode-space (width &rest props)
  "Return a single space string of WIDTH times the normal character width.
Optional argument PROPS specifies other text properties to apply."
  (apply 'propertize " " 'display (list 'space :width width) props))

(defun ruler-mode-ruler ()
  "Compute and return a header line ruler."
  (let* ((w (window-width))
         (m (window-margins))
         (f (window-fringes))
         (i 0)
         (j (window-hscroll))
         ;; Setup the scrollbar, fringes, and margins areas.
         (lf (ruler-mode-space
              'left-fringe
              'face 'ruler-mode-fringes
              'help-echo (format ruler-mode-fringe-help-echo
                                 "Left" (or (car f) 0))))
         (rf (ruler-mode-space
              'right-fringe
              'face 'ruler-mode-fringes
              'help-echo (format ruler-mode-fringe-help-echo
                                 "Right" (or (cadr f) 0))))
         (lm (ruler-mode-space
              'left-margin
              'face 'ruler-mode-margins
              'help-echo (format ruler-mode-margin-help-echo
                                 "Left" (or (car m) 0))))
         (rm (ruler-mode-space
              'right-margin
              'face 'ruler-mode-margins
              'help-echo (format ruler-mode-margin-help-echo
                                 "Right" (or (cdr m) 0))))
         (sb (ruler-mode-space
              'scroll-bar
              'face 'ruler-mode-pad))
         ;; Remember the scrollbar vertical type.
         (sbvt (car (window-current-scroll-bars)))
         ;; Create an "clean" ruler.
         (ruler
          (propertize
           (make-string w ruler-mode-basic-graduation-char)
           'face 'ruler-mode-default
           'local-map ruler-mode-map
           'help-echo (cond
                       (ruler-mode-show-tab-stops
                        ruler-mode-ruler-help-echo-when-tab-stops)
                       (goal-column
                        ruler-mode-ruler-help-echo-when-goal-column)
                       (ruler-mode-ruler-help-echo))))
         k c)
    ;; Setup the active area.
    (while (< i w)
      ;; Graduations.
      (cond
       ;; Show a number graduation.
       ((= (mod j 10) 0)
        (setq c (number-to-string (/ j 10))
              m (length c)
              k i)
        (put-text-property
         i (1+ i) 'face 'ruler-mode-column-number
         ruler)
        (while (and (> m 0) (>= k 0))
          (aset ruler k (aref c (setq m (1- m))))
          (setq k (1- k))))
       ;; Show an intermediate graduation.
       ((= (mod j 5) 0)
        (aset ruler i ruler-mode-inter-graduation-char)))
      ;; Special columns.
      (cond
       ;; Show the `current-column' marker.
       ((= j (current-column))
        (aset ruler i ruler-mode-current-column-char)
        (put-text-property
         i (1+ i) 'face 'ruler-mode-current-column
         ruler))
       ;; Show the `goal-column' marker.
       ((and goal-column (= j goal-column))
        (aset ruler i ruler-mode-goal-column-char)
        (put-text-property
         i (1+ i) 'face 'ruler-mode-goal-column
         ruler)
	(put-text-property
         i (1+ i) 'mouse-face 'mode-line-highlight
         ruler)
        (put-text-property
         i (1+ i) 'help-echo ruler-mode-goal-column-help-echo
         ruler))
       ;; Show the `comment-column' marker.
       ((= j comment-column)
        (aset ruler i ruler-mode-comment-column-char)
        (put-text-property
         i (1+ i) 'face 'ruler-mode-comment-column
         ruler)
	(put-text-property
         i (1+ i) 'mouse-face 'mode-line-highlight
         ruler)
        (put-text-property
         i (1+ i) 'help-echo ruler-mode-comment-column-help-echo
         ruler))
       ;; Show the `fill-column' marker.
       ((= j fill-column)
        (aset ruler i ruler-mode-fill-column-char)
        (put-text-property
         i (1+ i) 'face 'ruler-mode-fill-column
         ruler)
	(put-text-property
         i (1+ i) 'mouse-face 'mode-line-highlight
         ruler)
        (put-text-property
         i (1+ i) 'help-echo ruler-mode-fill-column-help-echo
         ruler))
       ;; Show the `tab-stop-list' markers.
       ((and ruler-mode-show-tab-stops (member j tab-stop-list))
        (aset ruler i ruler-mode-tab-stop-char)
        (put-text-property
         i (1+ i) 'face 'ruler-mode-tab-stop
         ruler)))
      (setq i (1+ i)
            j (1+ j)))
    ;; Return the ruler propertized string.  Using list here,
    ;; instead of concat visually separate the different areas.
    (if (nth 2 (window-fringes))
        ;; fringes outside margins.
        (list "" (and (eq 'left sbvt) sb) lf lm
              ruler rm rf (and (eq 'right sbvt) sb))
      ;; fringes inside margins.
      (list "" (and (eq 'left sbvt) sb) lm lf
            ruler rf rm (and (eq 'right sbvt) sb)))))

(provide 'ruler-mode)

;; Local Variables:
;; coding: iso-latin-1
;; End:

;;; arch-tag: b2f24546-5605-44c4-b67b-c9a4eeba3ee8
;;; ruler-mode.el ends here